Overload releasing mechanism



Mk'Ch 24, 1942. W C, MCCOY OVERLOAD RELEASING MECHANISM Filed Sept. l2,1940 5 Sheets-Sheet 1 March 24, 1942. W. c. MccoY OVERLOAD RELEASINGMECHANISM Filed Sept. l2, 1940 5 Sheets-Sheet 2 INVENTOR M LlLiam C. BY

ATTORNEYS March 24, 1942. W, c, MCCOY 2,277,554

OVERLOAD RELEASING MECHANISM Filed Sept. l2, 1940 5 Sheets-Sheet 5-INVENTOR WlI/iam C M9 foy BY v Vn/'M vd Vy- ATTORNEYS Fi d3 March 24,1942. W C, McCoy ovERLoAD RELEASING MEcHAN1sM Filed Sept. l2, 1940 5Sheets-Sheet 4 INVENTOR fil/Liam U. M Cof BY Va/M4 ATTORNE March 24,1942. w, c, MCcoY 2,277,554

ovERLoAD .RELEASING MEcHANhIsM Filed Sept. l2, 1940 5 Sheets-Sheet 5NVENTOR William L'. M@ @2y BY ma )Qa ATTORN EYS l. tented Man-24, 1942UNITED STATES PATENT OFFICE ovERLoAn nELEAsmG MEcnAmsM -Wimam c. McCoy,shaker Heights, om, as-

signer to The General Tire & Rubber Com-v pany, Akron, Ohio, acorporation of Ohio Application september 12, 1940, serial No. 56,421

. 15 claims. (ci. 1oz-5c)l This invention relates to driving mechanismsFig. 7 is a fragmentary side elevation showing and more particularly todriving mechanisms a modied form of valve controlling mechanism; havingrotatable driving and driven members Fig. 8 is a-fragmentary axialsection taken on connected by a flexible torque transmitting conthelineindicated at 8-8 in Fig. ,'7; nection, 5 Fig. 9 is a detail viewshowing the actuating The present invention has for its object to memberattached to the drum engaging tread utilize a flexible torquetransmitting connection portion of the inflatable shoe;

between driving and driven members to autoy Fig. 10 is a view partlyinelevation and partly matically control the application of driving forcein section showing an embodiment of the invento the driven members insuch manner as to I tion in which a valve actuator is controlled bydiscontinue the application of driving torque to an electric switch;

the driven member when the applied torque ex- Fig. 11 is a fragmentaryside elevation of the ceeds a predetermined maximum. switch and switchactuating means; v

A further object of the invention is to provide Fig. 12 is a sideelevation showing the invenan automatic control of the characterreferred l tion applied to a mechanically actuated-fluid to applied to adriving connection in which the pressureclutch;

torque is transmitted through a flexible inflated Fig. 13 is a sectiontaken on the line indicated annulus. v at l3|3 in Fig- 12;`

A further object is to provide a drive control Fig. 14 is a plan view ofthe clutch releasing which is responsive to relative circumferentialcollar; movements of portions `of the inflatable annulus Fig. 15 is aside elevation of the collar shown through which connections are madewith the in Fig. 14; v driving and driven members. Fig. 16 is a sideelevation of the collar actuat- A further object of the invention is toprovide ing ring with a part thereof broken away and a clutch of theinflatable shoe type which is 2.5 shown in section;

automatically released when overloaded. Fig. 17 isla fragmentary sideelevation of one A further object is to provide an overload drive of thering actuating levers; control which is not affected by starting torqueFig. 18 is a section taken on the line indicated but which becomeseffective after the driven at |8|8 in Fig. 12showing the clutch engaged;member attains a predetermined speed of rota- Fig. 19 is a sectionsimilarto Fig. 18 showing tion. the clutch disengaged; and

With the above and other objects in view the Fig. 20 shows a furthermodification of the invention may be said to comprise the device asinvention in which the control of the applicaillustrated in theaccompanying drawings heretion of driving force to the driven member isinafter described and particularly set forth in effected by controllingthe rapplication of power the appended claims, together with suchvariato the driving member. tiens and modifications thereof as will beap- The present invention utilizes the distortion parent to one skilledin the art to which the increated in a flexible torque transmittingmember vention appertains. Referencev should be had interposed between adriving member and a to thel accompanying drawings forming apartdrivenmember when subjected to excessive load of this specification, vinwhich: j to interrupt the transmission of driving force to Figure 1 is afragmentary side elevation of a the driven member. In the preferred formof fluid pressure clutch embodying the invention; the invention theflexible torque transmitting Fig. 2 is an axial section taken yon theline \member is an expansible shoe-containing'iluid indicated 'at 2-2 inFig. 1; 45 under' pressure and the transmission of driving lFig. 3 is aside elevation on an enlarged scale force is interrupted by controllingthe pressure cf the control valve actuating mechanism; within the shoeto break the drivingconnection.

Fig. 4 is an axial section taken on the line However, the inventioncontemplates the utilizaindicated at 4-4 of Fig. 3, showing the controltion of the distortion of the flexible torque transvalve inclutch-engaging position; mitting member to control a motor or otherprime Fig'. 5 is a section corresponding to that shown mover by whichthe mechanism is driven as is in Fig. 3, showing the control valve inthe clutch shown in Fig. 20 of the drawings.`

releasing position; Referring to Figsl to 6 of the drawings, the Fig. 6is a section taken on the line indicated invention 'is shown applied toa clutch of the in-v at 6 6 in Fig. 4; flatable shoe type interposedbetween a driving rubber having an interior base portion 9 atl tached tothe rim 1 of the supporting member and an exterior tread I D which isadapted to engage with the interior of the drum 3. The shoe 8 is moldedto a transversely elongated cross sectional form with its tread portionof lless diameter than the internal diameter of the drum so that whenuninflated the tread portion I is of less diameter than the drum and isout of engagement with the drum. However, when the uid under pressure issupplied to the interior of the drumy the tread I0 is expanded andpressed by uid' pressure against the interior of the drum. To supplypressure to the interior of the shoe the shoe 8 is provided with a stemII'which is connected to the base portion of the shoe, extends throughthe rim 1 and is connected to a valve casing I2. A pipe I3 connected tothe valve casing I2 communicates with an axial passage I4 in the shaft 2through which air under pressure may be supplied from a suitable source.The valve casing I2 is mounted in the web 6 of the shoe supportingmember and extends through the said web. The outer end of the casing I2is bored to receive a rotary control valve I5 which has a stem I6 whichextends through a gland I1 mounted in the outer end of the casing I2.The casing I2 has a port I8 which establishes communication with the airpipe I3 and the valve has a radial passage I9 adapted to register in oneposition of the valve with the port I8. The valve has a second radialpassage which is adapted to register in another position of the valvewithan exhaust port 2I in the casing I2. Thevalve I5 has an axial outlet22 extending from the radial passages I9 and 20 to the inner end of thevalve and registering with an aperture 23 in the casing I2 which opensinto an enlarged cylindrical chamber 24. A floating piston valve 25 ismounted in the chamber 24. The piston valve 25 is provided With an axialpassage which includes an opening 26 at its outer end and an enlargedchamber 21 in which is mounted a ball check valve 28 which is pressedagainst the opening 26 by a spring 29. At its inner end the valve 25 hasan. opening 30 through which air forced past the ball check valve passesto the outer end of the chamber 24 and through the stem I I to theinterior of the shoe, the stemr II being attached to a head 3l whichcloses the inner end of the chamber 24. When the valve I5 is in theposition shown in Figs, 4 and 6, air under pressure is admitted from thepipe I3 to the outer end of the chamber 24 and this pressure actingagainst the outer end of the piston valve 25 holds the piston valve 25against the head 3l and at vthe inner end of the chamber 24.` By reasonof the check valve 28 pressure in the outer end of the chamber 24 isslightly in excess of the pressure atthe inner end of the chamber andthis excess pressure is ample to normally hold the valve 25 in itsinnermost position.- In this position of the valve 25 the outer end ofthe chamber 24`receives air under pressure from the pipe I3 andmaintains pressure in the shoe 8 only slightly less than the pressureexisting in the line I3. If the valve I5 be turned in a clockwisedirection from the position shown in Fig. 6, to cause the radial passage20 to register with the outlet port 2l, the inlet port I8 is closed andthe air within the cuter end of the chamber 24 is permitted to escapethrough outlet 2I to the atmosphere. The release of pressure in theouter end of the chamber 24 causes the piston 25 to be moved to theouter end of the chamber, In which position of the piston valve a seriesof exhaust ports 32 adjacent the inner end of the casing I2 are openedpermitting air to escape from the shoe 8 to the atmosphere. Thedeflation of the shoe 8 will cause the tread I0 to be drawn inwardly outof contact with the drum 3 and break the driving connection.

In accordance with the present inventionl means is provided forautomatically actuating the valve I5 when an excessive load is imposedupon the driven shaft 2. The automatic valve actuating means will now bedescribed:

An actuating member 33 is fixed to the outer end of the valve stem I6.This member is provided with an arm 34 which projects radially inwardly.The inner end of thearm 34 is pivoted to a pin 35 which extends througha guide 36 mounted in a recess 31 in the hub 5 of the shoe supportingmember, the guide 36 being supported on trunnions 38 to permit rockingmovements of the pin .35. The arm 34 and pin 35 form a toggle interposedbetween the hub 5 and the valve stem I6, and aspring 39 interposedbetween the guide 36 and the outer end portion of the pin 35 exerts athrust on the togglev pivot, tending to swing the arm 34 in eitherdirection from the dead center position. In the normal position of thevalve I5 the toggle is close to its dead center position, being heldagainst an adjustable stop 40 which is in the form of a screw carriedbya. post 4I attached to the head 5.' The stop 40 is so positioned as topermit the arm 34 to swing slightly past dead center position so thatthe spring 39 will act to retain the arm 34 inengagement with the stop40, in which position of the arm the valve I5 connects the chamber 24with the supply pipe I3 to maintain pressure in the shoe 8. Theactuating member 33 is provided with an -outwardly projecting laterallyoffset arm 42 which carries an adjustable stop member 43 which may be inthe form of a screw, which is so positioned as to be in the path ofmovementof the trip arm 44 through which movement may be imparted to theactuating member 33. The trip arm 44 is pivoted to swing about the axisof the stem I6, being provided with a bearing ring 45 mounted upon theexterior of the casing I2, the bearing ring 45 being held in place by awasher 46 and -a locking ring 41. The outer end of the trip arm 44 isengaged by a yoke 48 which is fixed to the tread portion of the shoe 8.Whenever an excessive load is imposed uponl the driven shaft theincreased torsional thrust exerted through the flexible side walls ofthe annular shoe 8 will cause the tread portion Ill of the shoe to bemoved circumferentially with respect to the base portion which is xed tothe supporting member which carries the valve casing'l2. The relativeangular movement of the yoke 48 with respect to the casing I2 willimpart an angular movement to the trip arm 44. When this angularmovement is in excess of a predetermined amount the trip` arm 44 willlengage with the adjustable stop member 43, causing a rocking movementof the actuator 33 sufficient to move the yarm 44 away from the stop 40against which it is normally held and past dead center position,whereupon the spring 39 will move the arm 34 through a sumcient angle toconnect the chamber 24 with the exhaust port 2|, thereby causingactuation of the piston valve 25 and to release the pressure within theshoe`8. The extent of movement of the arm 34 outwardly away Afrom thestop'40 is limited by astop arm 49 attached to the actua r 33 andengageable with the outer end of the post 4|. The actuator may also' beprovided with a handle 59 by means of which the trip mechanism may bemanually reset.

In the modication above described a predetery mined torsional thrustexerted through the shoe 8 will Acause a circumferentially shifting ofthe tread portion I8 of the shoe sunlcient to trip the valve vactuatingmechanism and disengage the clutch.V In some installations it may bedesirable to disengage the machine from its driving mechanism, whenoperating at full speed in case the driving mechanism should'besubjected to overloads which are less than the overloads to which thedriving mechanism may be subjected instarting the machineryinto'operation'. In Figs. 7 and-8 of the drawings there is shown a tripmechanism applied to a lcontrolling valve of the same construction asthat 'previously described which is designed to operate only when thedriven member is rotating at substantially full speed, the trip devicebeing unaffected by overloads due to the inertia ofthe moving parts instarting. In this modification an actuating arm is fixed tothe valvestem I6 and the outer end of this arm is pivoted to a toggle link y52which is pivotally connected'to a second toggle link 53 which is pivotedat its outer end'to 'a shaft 54 xed to the web 6 of the shoe supportingmember. A trip arm 55 is also pivoted to the shaft 54 .at its inner endand its outer end is engaged by a yoke 56 fixed to the tread portion l0of the shoe. The toggle link 53 and the Atrip arm 55 are both freelyrotatable onthe shaft 54 and are connected by a coil spring 51 on theshaft 54 which has one end attached to the link 53 and its other endattached to the-trip arm 55. A spring 58 is attached at one. end to thearm 5| and at its opposite end to the hub 5 of the supporting member soa's to normally hold the arm 5| in its innermost position with thetoggle links 52 and 53 in substantially dead center position.

The spring 51 acting on the outer link. 52 'of the toggle serves tonormally hold the toggle with its pivot slightly past its dead centerposition, andv the link 53 in engagement with a stop pin 59 carried bythe web 6. The spring 58 serves to normally hold the arm 5| in itsinnermost position and to exert an endwise pullon the toggle links 52and 53 tending to hold them in alignment, While the spring 51 exertssuflicient lateral pressure on the link 53 to move the toggleA pivotslightly past dead center position and hold the link 53 against the stop59. The trip arm 55 has a laterally offset arm 69 which carries anadjustable toggle engaging member in the form-of `a screw 6| which isadapted, upon a predetermined movement of the arm to engage with thelink 53 and move the same away from the stop 59 a sumcient distance toshift the toggle pivot past dead center position so that an outwardthrust exerted upon the arm 5| may move the arm 5| to the dotted lineposition shown in Fig. 7 to shift the valve I5 to shoe releasingposition. A weight 52 is attached to the arm 5| andv this weight exertsan outward thrust due to centrifugal force when the driven member isrotated. When the driven member attains a predetermined speed ofrotation, Ithe outward force exerted by the weight 82 issumcient to movethe arm 5| outwardly against the action of the spring 5.8 whenever thevtoggle-formed by thelinks 52 and 53 is broken b y operation of thelever 55 under overload conditions; Breaking ofthe'toggle by the triparmv 55 while the machine is being started will not cause actuation ofthe valve because the outward vforce exerted by the weight 52 will notbe suilicient to overcome the action of the spring 58. However, when thedriven member attains operating speed an overload suiflcient to actuatethe trip arm` 55`and break the toggle will release the arm 5|, andcentrifugal force acting on the weight 52 will throw the arm outwardlyto move the valve l5 to shoe releasing position. In

order to prevent automatic reengagement of the clutch as the drivenmember slows down after release ofthe clutch, a suitable latch maybeprovided for retaining the arm 5| in clutch releasing position. Thelatch 63 ispivoted on the shaft l54 and backed by coil spring 64, beingso positioned as to engage with the outer end of the arm 5| to retain itin its outermost position. The latch '63 may be provided with a handley65 by means of which it may be actuated to release the arm 5| and thelatch may be positioned for engagement with the arm 5| by means ofthestop member 66 fixed to the web 6 and vagainst which the latch 53 isheld by the spring 64.

In Figs.`l0 and 11 'of the drawings a modification of the invention isshown in which a drum 61 is attached to the driving shaft and a drum 68to the driven shaft 2. `An annular inflatable shoe 69 has an 'exteriorbase portion 19 attached to the` interior of the drum 68 and an interiortread portion 1| which isengageable with the exterior rsurface of thedrum"61. Air under pressure may besupplied to the interior of the shoe69 through'a--passage 12 in the drum 68 which communicates with an axialpassage 13l in the driven shaft 2 which is connectedthrough a suitloneposition of the valve communication is established between the pipes 14and 16 and in the other position of the valve communication isestablished between the pipe 14and an exhaust port 11 in the valvecasing. In one position of the valve pressure is maintained within theshoe 69 .and in the other position of the valve pressure within theshoeis released. An axially disposed shaft 18 is mounted in the web of thedrum 68.

To the inner end of this shaft is xed an outwardly projecting arm 19which'is engaged at'its outer end lby a yoke 69 fixed to the treadportion 1| of the shoe 69. Exteriorly of the drum the shaft 18 carries atrip armv 8|, which is normally positioned inwardly of the movablecontact member of a switch 82 carried by a stationary bracket 8'3. Whenexcessive torsional load is irnposed upcn the shoe 69 an angularmovement is imparted to the arm 19, shaft 18, andv arm 8|, moving thearm 8| outwardly a sufficient distancev to cause vthe same to strikeagainst theyI movable contact Vmember of the switch 82 during rotationof the drum 68. The momentaryv closing of the trip arm 8| with theswitch 82 causes the valve 16 to be moved to pressure exhaustingposition; causing the air pressure to be released i'rom the interior ofthe shoe 69, freeing the shoe 69' which uid pressure within the clutchshoe is created by means of.a manually operated thrust applying device.In this clutch the outer drum 81 is attached to the shaft 2 and withinthis drum there is mounted an expansible shoe 88 which comprises anlouter casing 89 and an inner tube 90, the outer casing having a treadportion 9| engageable with the interior of the drum 81, short side walls92 and bead portions 93 mounted in seats 94 and 95 formed in the rimportions of supporting disks 96 and 91. The inner supporting disk 96 isattached to a sleeve 98 fixed to the shaft I and the outer supportingdisk 91 is supported by bolts 99 carried by the disk 96. The outer disk91 is slidable upon the bolts 99 and may be adjusted by means of nuts100 toward or away from the disk 96 to vary the clearance of the tread9| with respect to the interior of the drum 81. The interior wall of theinner tube 90 has a thickened central portion |I to` which metalsegments |02 are attached. On opposite sides of the metal segments |02the inner tube has relatively thin flexible portions |03 extendinginwardly between the disks 96 and 91. The portions of the inner tubeadjacent the seats 93 are also thickened so as to restrict the lateralflexing of the inner tube to constrain the center portion of the tube tosubstantially radial outward or inward movement. The inner tube 90 isfilled with liquid and pressure is created in the body of liquid withinthe tube by exerting the expanding force upon the central flexibleportion |0I of the inner tube 90. Radial outward pressure is exertedupon the inner tube 90 by thrust members |05 which`are interposedbetween a shifter collar |06 mounted for axial movement on the sleeve 98and the segments |02, the thrust members |05 having ball ends |01 and|08 seated in suitable spherical recesses in the collar and segments.When the clutch is disengaged the collar |06 is in its outermostposition and the thrust members |05 are at a substantial inclination tothe vertical. As the collar |06 is moved inwardly by means of a suitableshift lever (not shown) the thrust members |05 are moved toward aposition in which they lie in a plane perpendicular to the axis of theshaft I. In the perpendicular position of the thrust members |05, the

central portion IOI of the inner tube 90is expanded to the maximumextent. Pressure exerted on the body of liquid within the tube by theexpansion of the central portion of the inner walls of the inner tube 90is transmitted to the tread portion 9| of the shoe, expanding the sameinto engagement with the drum 81. The inward movement of the collar |06is limited by a flange |09 on the sleeve 98 and this flange is sopositioned that thrust members |05 may be moved with the collar |06slightly past their perpendicular position s0 that the contractileelasticity of the shoe positively holds the collar in its innermostposition, in which position of the collar the shoe is held in engagementwith the drum. In moving the collar |06 to disengage the clutch theinitial movement is resisted by the shoe, but as soon as the thrustmembers |05 have been moved past their perpendicular or dead centerposition, the elastic shoe due to its stretch will exert an outwardthrust on the actuating collar. The automatic releasing de vice of thepresent invention effects the release of the clutch by means of kickoutpins ||0 mounted in the flange |09 disposed parallel with the shaftV I.The pins ||0 are mounted for axial sliding movement in the ange |09 andare normally held in retracted position by means of a spring 'I I I.Movement' of the kick-out pins IIO is eected `by means of an actuatingcollar I I2 engaging the pins I I0 and slidably mounted on the sleeve98, the col1ar1||2 being h eld against turning movement on the sleeve bymeans of a pinI I3 carried by the sleeve 98 and engaging in alongitudinal slot III in the collar. The collar II2 has a cam portionIIB which is engaged by a cam II6 carried by a ring II1 which isrotatably mounted upon the sleeve 98 but which is held against slidingmovement on the sleeve by means of a retaining disk I I8'.- The ring ||1has external gear teeth ||9 which are .l

engaged by gear segments |20 carried by the inner kends of levers I2Iywhich are pivoted intermediate their ends on pivots |22 fixed to thedisk 96. The outer ends of the levers I2| are provided with slots |23which receive pins |24 fixed to the tread portion 9| ofthe shoe.- Whenthe expansible shoe 88 is subjected to excessive torsional stress due toan overload, the levers I2I are rocked about the pivots |22 and turningmovement is imparted to the ring II1 by means of 1the gearsegments |20.Turning movements of the ring 'I I1 moves the cam I I6 across theinclined face of the camportion I|5 of the collar II2, causing theactuating collar II2 to slide on the sleeve 98 and forcing the kick-outpins ||0 through the flange |09 against the collar |06, pushing thecollar |06 outwardly a suillcient distance to move the thrust members|05 past their perpendicular or dead center position.

In the modification shown in Fig. 20 the inflatable torque transmittingelement is utilized to control the motor or other prime mover whichoperates the driving shaft. The driving connecti'on shown in thismodification is like that shown in Figs. 10 and 1l, the drum 61abeingattached to the driving shaft I and the drum 68a to the drivenshaft 2. The two drums are connected by an inflatable shoe 69a which hasa base portion 10a attached to the drum 68a and a tread portion 1|aengageable with the drum 61a. The shaft 18ais mounted in the drum 68aand has an arm 19a fixed thereto and engaging in a yoke a fixed to thetread portion of the shoe 69a. The shaft 18a has a trip arm 8|a i'lxedto its outer end which in one position.is adapted to strike against themovable contact arm of a switch 82a which operates a relay switch 8|awhich closes the circuit of a solenoid |24 which controls a switch |25which opens and closes the circuit of a motor |26. When the driven shaftis overloaded the excessive torque exerted upon the shoe 69a actuatesthe trip arm 8|a, moving it to a position where it engages the movablecontact member of the switch 82a, momentarily closing the relay circuitto open the `switch 84a and deenergize the/solenoid |24 toopen theswitch |25 and stop the motor, the switch 84abeing retained in openposition until manually reset by a weight Furthermore, it is' to beunderstood that the particular form of apparatus shown and described,and the particular procedure set forth, are presented for purposes ofexplanation and illustration and that various modifications of saidapparatus and procedure can be made without ,departing from my inventionas denedbin the means carried by said irme!"memberior controlappendedclaims. l 4

WhatIclaimiSz E, g t 1.`Ina driving mechanism which comprises arotatable driving member.' a substantially coaxial rotatable drivenmember.` a connecting member in the form of a hollow iluid containinglannulus having oppositely disposed wall portions vadaptedv to bevconnected `for rotation with the drivingand driven members,respectively, and ilexible torque transmitting wall portions connectingsaid oppositely disposed wall portions, and means operable f upon apredetermined relative angular movement of yone of said oppositelydisposedvvall portions of the annulus with respect tothe other tocontrol the transmission of driving forceto the driven member.

2. In a driving mechanism which .comprises a rotatable, driving member,a substantially coaxial'rotatable driven member, aclutch'ior conlingsaid pressure applying means, and means ior actuating said ,controllingmeans includingamember attached tosaidshoe adjacent the .pe-

riphery thereof.,

6. A driving mechanism.comprisingfrotatable driving and ydriven.members.lMinna' carried byY v one oi.v said-members, an inilatable annuluspronecting said members comprising a hollow fluid containing annulushaving a peripheral wall attached to one of said members, its oppositeperipheral wall engageable with the other of said members and flexibletorque transmitting walls connecting said peripheral walls, means forcontrolling the pressure within said annulus to operate the clutch, andlmeans operable upon a prel determined relative angular movement of oneof said peripheral walls with respect totheoth'er due to the torque loadfor actuating said pressure controlling means.

3. `Ina driving mechanism which comprises` a rotatable driving member, asubstantiallycoaxial rotatable driven member, a clutch for connectingsaid members comprising aA hollow uid containing annulus having aperipheral wall attached to one of said members, its opposite peripheralwall engageable with the other of said members andilexible torquetransmitting walls connecting said peripheral walls, and automatic drivecontrolling means comprising a controlling element carried by the memberto which the annulus is attached and an actuating member operativelyassociated 'with said controlling, member and attached to said annulusadjacent the wall thereof which is engageable with the other of therotatable members.

4. In a driving mechanism which comprises a rotatable driving member, asubstantially coaxial rotatable driven member, a clutch for connecting adrum, an inner rotatable member substantially concentric withbthe drumand a exible elastic 'annular shoe carried by the inner member rotatabletherewith, said shoe having an exterior tread surface engageable withthe drum, a cirviding l.a driving L connectien 'between said members andhaving* a peripheral tread portionj engageable with thedrum, a baseportion Yspaced radially from saiddrumengaging tread portion andattached to theotherof said members, and l I flexible 4torquetransmitting sidewalls connecting the tread. and base portions. andmeansoperable upon a predetermined circumferential movement of the said treadportion oi the annulus'with respect tothe base portion thereof vforcontrolling the transmission of driving i'orce tothe driven, member. g'LA Vdriving driving and driven members, a ,drum carried by oneot'saidmembera an' inijlatable annulus vproviding a drivingconnectionbetween ,said members and havinga peripheral tread portion engageablewith the drum, a base portion. spaced radiallyirom said drum engagingtread portion and attachedtotheother of said members, and flexibleVtorque transmitting side walls connecting theA tread and base portions,means for-varying the fluid pressure `within said annulus to rengage ordisengage the annulus and drum, and means operably vassociated with saidcontrolling means and operable upon .a-,predetermined circumfer; entialmovement ,of said tread portion ot; the annulus with respectto `the`base portion thereof for vcmtrolling said pressure varying meanstodisengage the annulus from the drum.-

8. Aldriving mechanism comprisingrotatable driving and driven members,`a drum carried by one of said membersf an inflatable annulus providing adriving v,connection between said members and having a `peripheralftread portionl engageablewith the drum, abase portion spaced radiallyfrom said drumy engaging tread portion and atached to the pther of saidmembers, and iiexible torque transmitting side walls connecting thetread and base portions, valve controlled means for relieving the iiuidpressure in the annulus .to disengage the annulus from the drum, andmeans operable upona` predetermined circumferential movement ofv thetread portionvof the annulus with respect to the base portion thereof toactuate said valve.

9. A driving mechanism comprising rotatable driving and driven members,a drum carried by one of said members, an inflatable annulus providing adriving connection between said members and having a peripheral treadportion engageable with the drum, a base portion spaced radially fromsaid drum engaging tread portion and attached to the other of saidmembers, and

flexible torque transmitting side wallsconnectpressure varying means,and means including a member attached to the annulus adjacent the treadportion thereof for automatically actuating cumferentially flexible bodyportion, an interior r base portion attached to said inner member, ofshoe expanding means for exerting radial outward pressure upon said shoeto expand the same into engagement with the interior of the drum,

said controlling means upon a predetermined circumferential movement ofsaid tread portion of the annulus with respect to the base portionthereof.

mechanism comprising :rotatable 10. A driving mechanism comprising arotatable driving shaft, a drum attached to said driving shaft. a drivenshaft, an annular expansible shoe having a base portion attached to saiddriven shaft and a tread portion spaced radially from said base portionand engageable with said drum, said shoehaving a circumferentiallyflexible torque transmitting body portion between the base and treadportion thereof, means for expanding the shoe to engage the-treadportion thereof with the drum, and means operable upon a predeterminedcircumferential movement of the said tread portion of the annulus withrespect to the base portion thereof `for controlling the transmission ofdriving force to the driven member.

11."A driving mechanism comprising la rotatable driving shaft, a drumattached to said driving shaft, a driven shaft, an annular expansibleshoe having a base portion attached to said driven shaft and a treadportion spaced'radially from said base portionand engageable with saiddrum, said shoe having a circumferentially ilexible torque transmittingbody portion between the base and tread portion thereof, means forexpanding the shoe to engage the tread portion thereof with the' drum,means carried by the driven member for controlling the transmission ofdriving force to the driven member, and means for actuating saidcontrolling means comprising an actuating member attached to said shoe,a second actuating member mounted on the driven member, and meanscontrolled by the speed of rotation of the driven member for controllingthe operation of said actuating members.

12. A driving mechanism comprising a rotatable driving shaft, a drumattached to said driving shaft, a driven shaft, anannular expansibleshoe having a base portion attached to said driven shaft and a treadportion spaced radially from said base portion and engageable with saiddrum, said shoe having a circumferentially flexible torque transmittingbody portion between the base and tread portion thereof, means for ex--panding the shoe to engage the tread portion thereof with the drum,means carried by the driven member for controlling the transmission ofdriving force to the driven member, speed controlled means for actuatingsaid controlling means, and means carried by said shoe for controllingthe operation of said speed Ycontrolled means.

13. A driving mechanism comprising a rotatable driving shaft, a drumattached to said driving shaftha Idriven shaft, an annular expansibleshoe having a base portion attached to said driven shaft and a treadportion spacedradially from said base portion and engageable with saiddrum, said shoe having a circumferentially flexible torque transmittingbody portion between the base and tread portion thereof: means forexpanding the shoe to engage the tread portion thereof with the drum,means carried by the driven member for controlling the transmission ofdriving force to the driven member, an actuator for said controllingmeans carried by the driven member movable by centrifugal force upon apredetermined speed of rotation, means for normally holding saidactuator against movement, and means operable upon a predeterminedmovement of the tread portion of theshoe with respect to the baseportion thereof for releasing said actuator. v

14. A driving mechanism comprising rotatable driving and driven members,a drum carried by one of said members, an inatable annulus providing adriving connection between said members and having a peripheral treadportion engageable with the drum, a base portion spaced radially fromsaid drum engaging tread portion and attached to the other of saidmembers, and flexible torque transmitting side walls connecting thetread .and base portions, means for varying the fluid pressure withinsaid annulus to engage or disengage the annulus v`and` drum, axractuatoroperably connected to said pressurev varying means, said actuator beingcarriedby the driven member and movable by centrifugal force upon apredetermined speed of rotation in a direction to release the pressurein said annulus, and operable upon a predetermined movement of the treadportion of the annulus with respect to the base portion thereof forreleasing said actuator.

15. In a driving mechanism, a rotatable driving member, a rotatabledriven member, an elastic torque transmitting member connecting thedriving and driven members, means for controlling the application ofdriving force to said driven member, a speed controlled yactuator forsaid controlling means, and means responsive to the torque transmittedthrough said torque transmitting member for controlling said actuator.

WLLIAM c. MccoY.

